Pulsed-power technology controls biological growth, corrosion, and scale in process cooling systems using a tried-and-true technology: the laws of physics.

Bacteria Control. Pulsed-power devices impart pulsed, high-frequency electrical energy into flowing water by inducing time-varying, pulsed electric fields 2, 400 times per second. Pulsing an electric field in this way generates low-frequency, non-ionizing electromagnetic radiation. This radiation has a much lower frequency than microwave radiation (even lower than radio waves) but has a demonstrable effect on microorganisms. In a typical cooling tower setup, each bacterium experiences more than 20,000 pulses. The damage is sufficient to inhibit reproduction but not sterilize the system. The bacteria can recover in a few days, but they remain inactive while they are recirculating through the pulsed-power system. Total bacteria counts under pulsed-power control typically average less than 1,000 colony-forming units per milliliter.

Corrosion Control. In corrosion control applications, pulsed power technology offers an advantage over chemical treatment with respect to copper. While copper is resistant to most domestic waters, it is subject to pitting attack by either microbial growth or high levels of oxidizing biocides (chlorine, bromine). Typical chemical regimes use a triazole as a copper corrosion inhibitor to protect the copper from the oxidizing biocide. Triazoles form a protective film on the copper surface and protect the underlying metal. However, triazoles are attacked by oxidizing biocides and, if they are at too low a level, can actually acerbate localized galvanic attack by only partially covering the metal. A pulsed-power system eliminates these sources of corrosion while maintaining biological control without oxidizing biocides.

Scale Control. When calcium carbonate (limestone) and other dissolved minerals are concentrated through evaporation, they reach the level of saturation. Saturation is the level of concentration above which the water can hold no more minerals. At saturation, the minerals must precipitate out as a solid, using a surface as a starting point (i.e., heterogenous nucleation).

Pulsed power technology makes tiny suspended dust particles alternative sites for mineral precipitation through heterogeneous nucleation by removing the particles’ surface charge. The dust particles become coated with the solid mineral material, thus acting as a relief valve for over-concentration of minerals (super-saturation). The dust particles are the preferred sites for precipitation over equipment surfaces for two reasons. First, the dust particles are so plentiful that minerals encounter them before they encounter the equipment surfaces. Second, the suspended particles travel with the flowing water and therefore do not have to overcome relative velocity, as they would between an equipment surface and flowing water. The mineral-coated powder produced by the pulsed-power system is harmless and non-sticking.